I'm trying to get I2S audio output signals from AUDMUX5 on expansion connector (pins 88~100) to use an external DAC.
1) I commented the original mux configuration (to sgtl5000) into mx53_loco.c -> mx53_loco_pads
/* AUDMUX5 */
2) created the new pad mux into iomux-mx53.h
#define MX53_PAD_DISP0_DAT13__AUD5_RXFS IOMUX_PAD(0x3C0, 0x94, 3, 0x0, 0, NO_PAD_CTRL)
#define MX53_PAD_DISP0_DAT14__AUD5_RXC IOMUX_PAD(0x3C4, 0x98, 3, 0x0, 0, NO_PAD_CTRL)
#define MX53_PAD_DISP0_DAT16__AUD5_TXC IOMUX_PAD(0x3CC, 0xA0, 3, 0x0, 0, NO_PAD_CTRL)
#define MX53_PAD_DISP0_DAT17__AUD5_TXD IOMUX_PAD(0x3D0, 0xA4, 3, 0x0, 0, NO_PAD_CTRL)
#define MX53_PAD_DISP0_DAT18__AUD5_TXFS IOMUX_PAD(0x3D4, 0xA8, 3, 0x0, 0, NO_PAD_CTRL)
#define MX53_PAD_DISP0_DAT19__AUD5_RXD IOMUX_PAD(0x3D8, 0xAC, 3, 0x0, 0, NO_PAD_CTRL)
3) added this mux configuration into mx53_loco.c -> mx53_loco_pads
As a result :
- I don't have sound from the sgtl5000 (normal because I changed the mux configuration)
- I don't have LCD signal anymore on the corresponding pins(DISP0_DAT[13:19]) of the extension connector (normal because I changed the mux configuration)
- But I don't have I2S signal on these pins :(
4) Then I used IOMux.v2.0.27 to check the iomux configuration, and it said me that there was a conflict because VCC_LCD power rail should be at 3.3v
So I saw that VCC_LCD comes from PMIC DA9053 VLDO4.
I used regulator_set_voltage() then read it again with regulator_get_voltage, I read the good value but physically the voltage didn't change!
Two questions :
- Is it normal that I don't get I2S signals with 2.775V instead of 3.3V or is it an error in my mux configuration?
- How Can I change VLDO4 value?